U.S. patent number 8,036,655 [Application Number 12/785,151] was granted by the patent office on 2011-10-11 for clientless mobile subscribers with seamless roaming over scalable wide area wireless networks.
This patent grant is currently assigned to Nortel Networks Limited. Invention is credited to Fayaz Kadri, Hamid Mahmood, Kris Ng, Tricci So, Yusupha Touray, Donald Wade.
United States Patent |
8,036,655 |
Ng , et al. |
October 11, 2011 |
Clientless mobile subscribers with seamless roaming over scalable
wide area wireless networks
Abstract
System and method for seamless roaming over scalable wide area
Wireless LAN networks (WAWLAN) with clientless mobile subscribers.
A preferred embodiment comprises a wireless gateway (WG) coupled to
one or more access points in a wireless network to form a wireless
cluster (WC), a network access gateway (NAG) coupled to a wired
network, and a switch coupled to the WG and the NAG. Each wireless
cluster is a Wireless LAN Network (WLAN) with homogenous or
heterogeneous network architecture. The WG detects mobile nodes in
a wireless cluster and tracks mobile node location in the wireless
cluster. The NAG is an anchor point for mobile nodes in the WAWLAN
and maintains a fixed source of information about each mobile node
regardless of their mobility. The switch provides connectivity
between the NAG and the WG. Seamless roaming across Wireless LAN
network boundary by mobile subscribers without requiring special
mobility enabling client software.
Inventors: |
Ng; Kris (Kanata,
CA), So; Tricci (Kanata, CA), Touray;
Yusupha (Ottawa, CA), Wade; Donald (Kanata,
CA), Mahmood; Hamid (Kanata, CA), Kadri;
Fayaz (Kanata, CA) |
Assignee: |
Nortel Networks Limited
(Mississauga, CA)
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Family
ID: |
36944060 |
Appl.
No.: |
12/785,151 |
Filed: |
May 21, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20100226336 A1 |
Sep 9, 2010 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11271632 |
Jun 15, 2010 |
7738424 |
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60627437 |
Nov 12, 2004 |
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60688584 |
Jun 8, 2005 |
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Current U.S.
Class: |
455/432.1;
370/420; 709/227; 709/204; 709/209; 370/400; 455/445; 370/469;
370/390; 370/389; 455/452.2; 709/230; 370/525; 370/341; 709/229;
709/217; 709/202; 370/331; 370/367 |
Current CPC
Class: |
H04W
92/24 (20130101); H04W 64/00 (20130101); H04W
36/18 (20130101); H04W 4/12 (20130101); H04W
84/12 (20130101); H04W 88/16 (20130101) |
Current International
Class: |
H04W
4/00 (20090101) |
Field of
Search: |
;455/432.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Perez-Gutierrez; Rafael
Assistant Examiner: Arevalo; Joseph
Attorney, Agent or Firm: Slater & Matsil, L.L.P.
Parent Case Text
This application is a continuation of U.S. patent application Ser.
No. 11/271,632, entitled "Clientless Mobile Subscribers With
Seamless Roaming Over Scalable Wide Area Wireless Networks," filed
on Nov. 10, 2005, which claims the benefit of U.S. Provisional
Application No. 60/627,437, filed Nov. 12, 2004, entitled "Scalable
Clientless Mobile Subscribers Seamless Roaming Over Wide Area
Wireless Mesh Network," and Application No. 60/688,584, filed Jun.
8, 2005, entitled "Scalable Clientless Mobile Subscribers Seamless
Roaming Over Wide Area Wireless Mesh Network and Wireless LAN
Network," which applications are hereby incorporated herein by
reference.
Claims
What is claimed is:
1. A network comprising at least two wireless networks, said at
least two wireless networks supporting roaming and comprising: a
wireless gateway comprising a plurality of wireless gateway
circuits coupled to a plurality of wireless network access points
to form a plurality of wireless clusters, a first one of said
plurality of wireless gateway circuits and a first plurality of
access points defining a first wireless cluster and a second one of
said plurality of wireless gateway circuits and a second and
different plurality of said access points defining a second
wireless cluster, the wireless gateway configured to track the
location of a plurality of mobile nodes in the wireless clusters,
wherein first and second tracked mobile nodes of said plurality
support only one of, respectively, first and second different
networking architectures and/or topologies, and said wireless
gateway is further configured to track said mobile nodes from a
first access point in a wireless cluster to another access point in
the wireless cluster, said first tracked mobile node communicating
with access points in said wireless gateway according to said first
networking architecture and/or topology and said second tracked
mobile node communicating with access points in said wireless
gateway according to said second networking architecture and/or
topology; a network access gateway coupled to a wired network, the
network access gateway comprising first and second network access
gateway circuits, said first network access gateway circuit only
supporting said first networking architecture and/or topology and
said second network access gateway circuit only supporting said
second networking architecture and/or topology, and said network
access gateway configured to be an anchor point for said plurality
of mobile nodes in the wireless network, to maintain a fixed source
of information about each mobile node in said wireless clusters as
the mobile nodes roam from a wireless cluster to another wireless
cluster, and to direct incoming and outgoing traffic to and from
the mobile nodes; and a switch coupled to the wireless gateway and
the network access gateway, the switch configured to provide
connectivity between the network access gateway and the wireless
gateway.
2. The network of claim 1, wherein each of the plurality of
wireless networking access points supports a different networking
architecture and/or topology.
3. The network of claim 1, wherein the at least two wireless
networks are based on IEEE 802.11 compliant radio technology.
4. The network of claim 1, wherein the network includes at least
one wireless gateway for each wireless network.
5. The network of claim 4, wherein a wireless gateway that is
associated with a wireless cluster is responsible for tracking
mobile nodes only within the wireless cluster associated with the
wireless gateway.
6. The network of claim 1, wherein the network includes a plurality
of network access gateways, each network access gateway configured
to be an anchor point, maintain a fixed source of information, and
direct traffic for a subset of mobile nodes.
7. The network of claim 6, wherein the network further includes a
plurality of wireless gateways, and wherein a network access
gateway remains associated with a mobile node even if the mobile
node moves from a first wireless gateway to a second wireless
gateway.
8. The network of claim 6, wherein a mobile node is assigned an
Internet Protocol (IP) address upon association with the network,
and wherein the mobile node is associated with a network access
gateway based on the IP address.
9. The network of claim 8, wherein the mobile node maintains the
assigned IP address for an entirety of time that it is associated
with the network.
10. The network of claim 1, wherein the wireless gateway, the
network access gateway, and the switch provide support for a
predetermined number of mobile nodes, wherein additional wireless
gateways, network access gateways, and switches are added to the
network to support a number of mobile nodes, and wherein the number
of mobile nodes is greater than the predetermined number of mobile
nodes.
11. The network of claim 1, wherein a first device addressing
technique is used to address packets flowing between the wireless
gateway, the network access gateway and the switch and a second
device addressing technique is used to address packets flowing
between the wireless gateway and the mobile nodes, and wherein the
first device addressing technique is different from the second
device addressing technique.
12. The network of claim 1 wherein the first and second different
networking architectures and/or topologies are proprietary
networking architectures and/or topologies.
13. In a network comprising a wireless gateway including a
plurality of wireless gateway circuits coupled to a plurality of
wireless network access points to form a plurality of wireless
clusters, a first one of said plurality of wireless gateway
circuits and a first plurality of access points defining a first
wireless cluster and a second one of said plurality of wireless
gateway circuits and a second and different plurality of said
access points defining a second wireless cluster, the wireless
gateway configured to track the location of mobile nodes in the
wireless clusters, wherein first and second tracked mobile nodes of
said plurality support only one of, respectively, first and second
different networking architectures and/or topologies, and said
wireless gateway is further configured to track said mobile nodes
from a first access point in a wireless cluster to another access
point in the same wireless cluster, said first tracked mobile node
communicating with access points in said wireless gateway according
to said first networking architecture and/or topology and said
second tracked mobile node communicating with access points in said
wireless gateway according to said second networking architecture
and/or topology, a method for communicating in the network, the
method comprising: establishing a session for a mobile node in the
network, wherein information regarding a routing of packets to the
mobile node is stored in a fixed location in the network,
independent of a location of the mobile node; and permitting the
mobile node to enter an operating mode.
14. The method of claim 13 further comprising, optionally
authenticating the mobile node.
15. The method of claim 13, wherein the establishing comprises
decoding an address for the mobile node to determine the fixed
location.
16. The method of claim 15, wherein the fixed location is a network
access gateway, and wherein the fixed location is used to store
configuration information determined by an address of the mobile
node.
17. The method of claim 13 further comprising after the permitting,
updating the information at the fixed location if the mobile node
has roamed to a different portion of the network.
18. The method of claim 17, wherein each wireless cluster of said
plurality is associated with a wireless gateway, and wherein the
updating comprises: decoding an address for the mobile node to
determine the fixed location; and providing configuration
information of the mobile node to the fixed location.
19. The method of claim 13, wherein the fixed location is used to
store configuration information determined by an address of the
mobile node, and wherein the address of the mobile node remains
constant as the mobile node roams about the network.
20. The method of claim 13 wherein the first and second different
networking architectures and/or topologies are proprietary
networking architectures and/or topologies.
Description
TECHNICAL FIELD
The present invention relates generally to a system and a method
for digital communications, and more particularly to a system and a
method for seamless roaming over scalable wide area Wireless LAN
networks (WAWLAN) with clientless mobile subscribers.
BACKGROUND
Wireless LAN (WLAN) networks can provide subscribers with an
unprecedented degree of mobility and flexibility. However, a
typical Wireless LAN network deployment (such as a hot spot,
campus, or enterprise environment) provides limited roaming
coverage due to a limited range of WLAN access points. A large
scale implementation of a WAWLAN network may also present
challenges, including maintaining a mobile subscriber's service and
connectivity while the mobile subscriber crosses WLAN network
boundaries (roams within the WAWLAN).
Additionally, there exist many implementation options available
when using multiple networking architectures in deploying WLANs,
such as, control and management intelligence residing in the access
point (AP) itself (sometimes referred to as thick AP architecture),
control and management intelligence residing in a controller within
the WLAN but outside of the APs (sometimes referred to as thin AP
architecture), and Wireless Mesh technology. Furthermore, roaming
across a wide area network comprising different WLAN architectures
presents another challenge in maintaining a mobile subscriber's
service and connectivity while crossing WLAN boundaries.
A desire may then exist to create a WAWLAN, comprised of different
WLAN architectures, that is capable of providing wireless access to
a variety of mobile nodes (subscribers). The ability to permit
mobile nodes access to the WAWLAN regardless of how the WLAN
networks are implemented can increase the subscriber base, thereby
increasing the potential profitability of the WAWLAN operators.
Additionally, to help reduce financial exposure in the deployment
of a wireless network, an initial deployment of the WAWLAN may be
limited in size and scope with the flexibility to choose the WLAN
deployment architecture that is most suitable for supporting an
initial customer base. As the number of subscribers increases, the
WAWLAN can be expanded to support the increased number of
subscribers. The expansion of the WAWLAN may comprise adding
additional WLANs of the same networking technology or of a
different networking technology.
One solution that can be used to support different networking
technologies in a single WAWLAN is to make use of mobility enabling
software applications that can be installed in each mobile node.
The software applications (commonly referred to as mobility
clients) installed in the mobile nodes can permit the mobile node
the ability to communicate with the WAWLAN, regardless of what
networking technology being implemented in a particular portion of
the WAWLAN.
A disadvantage of the prior art that the inclusion of a mobility
client in each of the mobile nodes may result in situations wherein
a mobile node may not have the proper mobility client installed and
may not be able to obtain access to the WAWLAN.
Another disadvantage of the prior art is that the installation of
the mobility client application may tax mobile nodes with limited
processing power or capability and may preclude their use in the
WAWLAN or may limit their performance to a level that is
unacceptable.
Yet another disadvantage of the prior art is that the wireless
network operator must deploy network elements in the WAWLAN in
support of the mobility client to enable mobile subscribers roam
across the wide area Wireless LAN network. The additional
hardware/software can require a large expenditure in maintenance
and support. Furthermore, the lack of scalability of such a
solution is not conducive to future expansion of the WAWLAN.
SUMMARY OF THE INVENTION
These and other problems are generally solved or circumvented, and
technical advantages are generally achieved, by preferred
embodiments of the present invention which provides a system and a
method for seamless roaming over scalable wide area Wireless LAN
network with clientless mobile subscribers.
In accordance with a preferred embodiment of the present invention,
a network is provided. The network includes a wireless gateway
coupled to one or more wireless network access points in a wireless
network to form a wireless cluster, a network access gateway
coupled to a wired network, and a switch coupled to the wireless
gateway and the network access gateway. The wireless gateway tracks
mobile node location in the wireless cluster, detects the presence
of mobile nodes in the wireless cluster, and directs message
traffic, while the network access gateway is an anchor point for
mobile nodes in the wireless network, maintains a fixed source of
information about each mobile node regardless of the mobility of
the mobile node, and directs incoming and outgoing traffic to and
from the mobile nodes. The switch provides connectivity between the
network access gateway and the wireless gateway.
In accordance with another preferred embodiment of the present
invention, a method for communicating in a network is provided. The
method includes establishing a session for a mobile node in the
network and permitting the mobile node to enter an operating mode,
wherein information regarding a routing of packet to the mobile
node is stored in a fixed location in the network, independent of a
location of the mobile node.
An advantage of a preferred embodiment of the present invention is
that clientless roaming is provided, which does not require client
applications to be loaded into mobile nodes to support roaming
within the WAWLAN. Additionally, seamless roaming is supported so
that a mobile node can travel within the operating range of the
WAWLAN (ranging from hot spot (small scale) to city-wide public
access (large scale)) and move across subnets without requiring
user intervention.
A further advantage of a preferred embodiment of the present
invention is that the WAWLAN is scalable to support large numbers
of mobile nodes without significantly increasing the complexity of
the wireless WAN by incrementally integrating WLANs of different
architectures. This can enable an initial rollout of the WAWLAN
with a small operating area and then rapidly and easily increase
the capacity of the WAWLAN as subscribers increase.
Yet another advantage of a preferred embodiment of the present
invention is that standard, off-the-shelf hardware and software can
be used to implement the wireless WAN, further decreasing the cost
of implementing the WAWLAN. Furthermore, since the hardware and
software are already available, they are well tested and debugged.
Therefore, the cost of the WAWLAN can further be reduced since
testing and operating support for the WAWLAN need not be extensive
as if all new hardware and software were used in the WAWLAN.
The foregoing has outlined rather broadly the features and
technical advantages of the present invention in order that the
detailed description of the invention that follows may be better
understood. Additional features and advantages of the invention
will be described hereinafter which form the subject of the claims
of the invention. It should be appreciated by those skilled in the
art that the conception and specific embodiments disclosed may be
readily utilized as a basis for modifying or designing other
structures or processes for carrying out the same purposes of the
present invention. It should also be realized by those skilled in
the art that such equivalent constructions do not depart from the
spirit and scope of the invention as set forth in the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention, and the
advantages thereof, reference is now made to the following
descriptions taken in conjunction with the accompanying drawings,
in which:
FIG. 1 is a diagram of a wide area Wireless LAN network
(WAWLAN);
FIGS. 2a through 2c are diagrams of a tiered hierarchy WAWLAN with
support for clientless mobile nodes and seamless roaming, according
to a preferred embodiment of the present invention;
FIG. 3 is a diagram of a detailed view of the tiered hierarchy
WAWLAN, according to a preferred embodiment of the present
invention;
FIG. 4 is a diagram of a sequence of events describing the
operation of a mobile node in the WAWLAN, according to a preferred
embodiment of the present invention; and
FIGS. 5a through 5d are diagrams of sequences of events describing
the operations of the mobile node in the WAWLAN, according to a
preferred embodiment of the present invention.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
The making and using of the presently preferred embodiments are
discussed in detail below. It should be appreciated, however, that
the present invention provides many applicable inventive concepts
that can be embodied in a wide variety of specific contexts. The
specific embodiments discussed are merely illustrative of specific
ways to make and use the invention, and do not limit the scope of
the invention.
The present invention will be described with respect to preferred
embodiments in a specific context, namely a wide area Wireless LAN
network (WAWLAN) comprised of wireless mesh connected networks,
and/or wireless local area networks (WLANs) with different
networking implementations (including but not limited to:
traditional thick AP architecture with control and management
intelligence residing in the access point itself, and thin AP
architecture with control and management intelligence residing in a
controller within the Wireless LAN network but outside of the
access points). The invention may also be applied, however, to
other instantiations of WAWLANs wherein the encompassing WLAN
networks may be homogeneous or heterogeneous.
With reference now to FIG. 1, there is shown a diagram illustrating
an exemplary WAWLAN 100. In order to provide a wide coverage area,
the WAWLAN 100 can have multiple Wireless LAN networks, such as
wireless network-1 105, wireless network-2 106, wireless network-3
107, and wireless network-N 108. Each of the individual WLAN
networks may have a unique topology, a common topology, or some
combination thereof. For example, the wireless network-1 105 may
have a mesh network, while the wireless network-2 106 may have a
thick AP architecture wireless local area network (WLAN)
topology.
The wireless networks of the WAWLAN 100 can be coupled to a wired
network 110. The wired network 110 can provide an infrastructure
that can permit the individual wireless networks to communicate
with each other as well as provide connectivity to other networks,
such as the Internet, corporate networks, private commercial
networks, and so forth. Additionally, the wired network 110 can
provide connectivity to services such as authentication services,
accounting services, authorization services, and so forth.
The WAWLAN 100 can be used to provide connectivity to subscribers
through the use of mobile nodes, such as a mobile node 115. A
mobile node may be a device that can connect to the WAWLAN 100 and
source and/or sink information. For example, a mobile node may be a
simple device that only receives information, such as financial,
weather, news, and so forth. Alternatively, a mobile node may be a
personal computer, Wi-Fi telephone, personal digital assistant, and
so on, that can also provide information as well as receive
information.
As the subscriber makes use of a mobile node, such as the mobile
node 115, the subscriber may move out of an operating range of a
first wireless network and into an operating range of a second
wireless network. For example, as shown in FIG. 1, the mobile node
115 may initially be communicating with the wireless network-1 105.
However, as the subscriber moves around, the mobile node 115 may
move out of the operating range of the wireless network-1 105 and
into the operating range of the wireless network-3 107 (shown as a
dotted link labeled "1"). Then as the subscriber continues to move,
the mobile node 115 may move into the operating range of the
wireless network-2 106 (shown as a dashed link labeled "2").
In the past, when a mobile node changes from communicating with a
first wireless network to a second wireless network, when the two
wireless networks are implemented using different networking
technologies, the subscriber may experience network connectivity
interruption and/or service degradation. Subscriber satisfaction
may degrade, especially in fringe areas where the subscriber needs
to frequently make changes, while if client applications are
needed, then a minimum complexity required for mobile nodes may
exceed existing mobile nodes and prevent their use. A need is
therefore present for a WAWLAN that can support clientless mobile
nodes and seamless roaming.
With reference now to FIGS. 2a through 2c, there are shown diagrams
illustrating high level views of a WAWLAN 200 that makes use of a
tiered hierarchy to provide support for clientless mobile nodes and
seamless roaming, according to a preferred embodiment of the
present invention. The diagram shown in FIG. 2a illustrates that
the WAWLAN 200 includes a wired network 205 and one or more
wireless networks 210. The WAWLAN 200 provides access to
information and services to subscribers making use of mobile nodes,
such as mobile node 115. In order to provide support for clientless
mobile nodes and seamless roaming, a two-tiered hierarchy of anchor
points overlaying a distributed network is used. A first tier 215,
labeled "tier-1," can function as anchor points for subsets of
mobile nodes in the WAWLAN 200 and a second tier 220, labeled
"tier-2," can function as gateways for mobile node access points
(also referred to as wireless access points (WAP) or simply access
points (AP)) to create wireless clusters (WC). The first tier 215
can be responsible for macro-mobility that keeps track of which WC
with whom each mobile node is currently communicating and the
second tier 220 can be responsible for micro-mobility that keeps
track of which WAP with whom the mobile node is currently
communicating.
The diagram shown in FIG. 2b illustrates a network layer view of
the WAWLAN 200. Between the wired network 205 and the wireless
networks 210, there may exist a wired network access layer 250 and
a wireless network layer 255. The wired network access layer 250
can provide access to and from the wired network 205, while the
wireless network access layer 255 can provide access to and from
the wireless networks 210 and mobile nodes 115. Coupling the wired
network access layer 250 and the wireless network access layer 255
is a switching transport layer 260. The switching transport layer
260 can provide necessary packet switching needed to transmit a
packet between the wired network 205 and the wireless networks 210.
The wired network access layer 250 and a portion of the switching
transport layer 260 make up the first tier 215 of the wireless WAN
200 and the wireless network access layer 255 and a portion of the
switching transport layer 260 make up the second tier 220 of the
WAWLAN 200.
The diagram shown in FIG. 2c illustrates a functional block view of
the WAWLAN 200. The wired network access layer 250 can be
functionally implemented as a network access gateway (NAG) 275,
which can perform tasks such as being an anchor point for mobile
nodes, which can entail maintaining information regarding which
wireless network is associated with each mobile node, controlling
and directing incoming and outgoing network traffic to and from
mobile nodes, subscriber authentication, and so forth. The wireless
network access layer 255 can be implemented as a wireless gateway
(WG) 280 which can include one or more WLAN access points (not
shown). The WG 280 and the WLAN access points can be used to form
wireless clusters (WC), and the WG 280 can function as an anchor
point to all mobile nodes associated with each WC. Furthermore, the
WG 280 can keep track of the location of mobile nodes in the WC and
informing the NAG 275 of each mobile node's WC association. The
switching transport layer 260 can be implemented using an Ethernet
switch 285. A network operation support system (NOSS) 290 can be
connected to the wired network 205 to provide needed network
management functionality to the WAWLAN 200.
With reference now to FIG. 3, there is shown a diagram illustrating
a detailed view of the WAWLAN 200, according to a preferred
embodiment of the present invention. In order to support
scalability of the WAWLAN 200, the NAG 275, the WG 280, and the
Ethernet switch 285 can be implemented using circuitry that can
permit the incremental addition of additional similar functioning
circuitry to increase the ability of the WAWLAN 200 to support a
larger number of mobile nodes 115. For example, the NAG 275 may be
implemented with multiple circuits, such as NAG-1 305, that can
perform the functions of a NAG for a certain number of mobile
nodes. Similarly, Ethernet switch-1 320 and WG-1 310 can provide
Ethernet switching and wireless gateway functionality for specified
number of mobile nodes. Should there be a desire to increase the
number of mobile nodes to be supported by the WAWLAN 200,
additional circuitry can be added to the AG 275, the WG 280, and
the Ethernet switch 285.
In order to provide support for a two-tiered hierarchy, the WG 280
can be used to provide functionality, including: mobile node
location tracking while connected to a WC through an AP, informing
a mobile node's anchor, NAG 275, when a mobile node is detected
within the WC, informing APs in the WC when a mobile node leaving
the WC is detected, maintaining mapping between a mobile node's IP
address and the mobile node's anchor NAG (a NAG specifically
associated with a mobile node), directing mobile node traffic
towards its anchor NAG, and so forth. Mobile node tracking can be
performed by the WG 280 via techniques such as by performing a
mobile IP (MIP) home agent function, IEEE 802.11f "Inter-Access
Point Protocol" L2 update frames, IEEE 802.11 MAC layer primitives,
and so on.
To provide reliable performance in the presence of potential
failures, the NAG 275, WG 280, and Ethernet switch 285 can be
backed up with at least one duplicate circuit that can be
automatically switched into service in case of failure. Although
shown in FIG. 3 as being a fully redundant system, with a
replacement present for each circuit in the NAG 275, WG 280, and
Ethernet switch 285, a potentially more efficient fault-tolerant
system can be implemented wherein a pool of redundant replacements
can be present and then when a failure is detected, a replacement
can be switched in.
A mobile node is associated to its anchor NAG by its IP address.
For example, an anchor NAG may be responsible for all mobile nodes
with an IP address that matches 192.1.X.X and a second anchor NAG
is responsible for all mobile nodes with an IP address matching
192.2.X.X. If multiple NAGs are responsible for one set of mobile
nodes, for example, for fault tolerance purposes, then only one of
the NAGs will function as a primary access NAG and the remainder
will be standby units that will take over if the primary access NAG
fails.
With reference now to FIG. 4, there is shown a diagram illustrating
a sequence of events 400 describing the operation of a mobile node
in the WAWLAN 200, according to a preferred embodiment of the
present invention. A mobile node, such as the mobile node 115 (FIG.
1), being used by a subscriber, must undergo a series of events
before it can begin operating in the WAWLAN 200. The sequence of
events 400 describes one such series of operations for a typical
mobile node.
The sequence of events 400 can begin with the mobile node 115 being
powered on (block 405). As the mobile node 115 is powered on, it
undergoes an initialization phase, which can include configuring
its radio frequency circuitry, testing various circuits and
memories, acquiring a radio frequency signal (such as a beacon or a
synchronization signal) to enable it to join the WAWLAN 200, and so
forth. Although the mobile node 115 may perform all of these tasks
when it is powered on, it may also periodically perform these tasks
(with perhaps exception given to the configuration of its radio
frequency circuitry and testing of various circuits and memories)
when it is powered on but not having been able to join the WAWLAN
200.
After the mobile node 115 has been powered on (block 405) and
having been able to join the WAWLAN 200, the mobile node 115 can
undergo an optional authentication operation (block 410). The
authentication operation is to ensure that the mobile node 115 (and
hence its user, the subscriber) has permission to make use of the
WAWLAN 200. The authentication may verify the identity of the
subscriber, check the status of the subscriber's account, and so
forth. The authentication operation is optional since in an open
network, it may not be necessary to verify the identity of the
mobile node 115. Once authenticated, the mobile node 115 can
establish a session with the WAWLAN 200 (block 415). The session
established can depending upon the nature of the subscriber's
account, the capabilities of the mobile node 115, the capabilities
of the wireless network that the mobile node 115 has connected
with, and so forth. The establishment of the session can involve
the storage of information pertaining to a routing of packets to
the mobile node 115 in a fixed location. The storage of the
information will be discussed in greater detail below. Once the
session has been established, the mobile node 115 can enter an
operating mode (block 420), which can include sending and receiving
packets, roaming, and so on. If there are changes to mobile node
115, such as when the mobile node 115 roams to a different portion
of the WAWLAN 200, then information regarding a routing of packets
to the mobile node 115 can be updated.
With reference now to FIG. 5a, there is shown a diagram
illustrating a sequence of events 500 in a mobile node 115 powering
up and establishing a session with the WAWLAN 200, according to a
preferred embodiment of the present invention. According to a
preferred embodiment of the present invention, the sequence of
events 500 provides a detailed description of events 405 and 415
shown in FIG. 4. The sequence of events 500 can begin with the
mobile node 115 powering up within an operating area of the WAWLAN
200 (block 502). As discussed previously, the mobile node 115 may
have already been powered on and moved into the operating area of
the WAWLAN 200. As the mobile node 115 powers up (or moves into)
the operating area of the WAWLAN 200, the mobile node 115 can be
detected by an access point (AP), such as AP-1 (not shown), of a
wireless cluster (WC), such as WC-1 (not shown) (block 504).
Although not shown in FIG. 5a, the mobile node 115 may then undergo
an optional authentication process.
The mobile node 115 can then acquire an Internet protocol (IP)
address (block 506). The mobile node 115 may acquire the IP address
from a server or an application. For example, the mobile node 115
may transmit a configuration request to a dynamic host
configuration protocol (DHCP) server (not shown) and the DHCP
server can return to the mobile node 115 configuration information,
including the IP address. Furthermore, the DHCP server can also
provide a vendor specific value to indicate the mobile node's
network access gateway (NAG) address. DHCP and DHCP servers are
considered to be well understood by those of ordinary skill in the
art of the present invention and will not be discussed herein. When
the mobile node 115 acquires the IP address, the mobile node 115
will maintain the IP address until its session with the WAWLAN 200
is terminated. The mobile node 115 will maintain the IP address
even if it roams out of its current WC into another WC.
After the mobile node 115 acquires the IP address, a wireless
gateway (WG), such as the WG-1 310 (FIG. 3), can detect the
presence of the mobile node 115 in the WC and obtain the mobile
node's IP address (block 508). The WG detects presence of a mobile
node within its subtending WC by means of technique specific to the
network architecture of the wireless cluster. These techniques
(such as MIP registration, IEEE802.11f L2 update, IEEE 802.11 MAC
primitives) are considered well understood by those of ordinary
skill in the art of the present invention and will not be discussed
further herein. For example, one way for the WG to detect the
presence of the mobile node 115 and obtain its IP address could be
for the AP to send a mobile node registration request to the WG.
The mobile node registration request can also be referred to as an
MIP (mobile IP) registration request. The mobile node registration
request may include a NAG address (which can be the same as the
default gateway IP address) and a home-agent address (which may be
provided by the DHCP server), for example. The WG can perform
processing of the mobile node registration request, which can
include: extracting a NAG IP address from the mobile node's
registration request; if the NAG (from NAG IP address) is currently
offline, then rejecting the registration request; if the NAG is
active, then updating information related to the mobile node to
include the NAG IP address; if the registration request results in
a creation of a binding for a new mobile node, then informing other
WGs of new binding.
The WG will create a mobility binding the first time that the
mobile node 115 associates with the AP within a given WC. It also
informs other WGs of the new binding, as well as the mobile's
anchor NAG to indicate to that the mobile node currently roams into
the coverage area of the WG. If the mobile node 115 already has a
mobility binding, then the mobility binding can be updated. When a
mobility binding is updated, the WG will inform the anchor NAG of
the mobile node 115 of the update. The WG can make use of a Unicast
ARP (address resolution protocol) message to send the updated
mobility binding to the anchor NAG, for example.
After detecting the mobile node 115 and obtaining its IP address
(block 508), the WG can send the information to a network access
gateway (NAG) that is functioning as an anchor NAG for the mobile
node 115 (block 510). For example, the WG can send the mobile
node's information to the anchor NAG, wherein the anchor NAG is the
NAG specified by the NAG IP address from the mobile node's
registration request. The WG can make use of a Unicast ARP (address
resolution protocol) message to send the mobile node's information
to the anchor NAG, for example.
With reference now to FIG. 5b, there is shown a diagram
illustrating a sequence of events 520 in a mobile node 115 roaming
between two wireless gateways of the WAWLAN 200, according to a
preferred embodiment of the present invention. The sequence of
events 520 provides a detailed description of events occurring when
a mobile node 115 roams from a first WG, such as WG-1, to a second
WG, such as WG-2. The sequence of events 520 can begin with the
mobile node 115 powering up within the operating area of the WAWLAN
200 (block 522). The sequence of events 500 (FIG. 5a) can be
referenced for a description of the power up sequence for a mobile
node in the WAWLAN 200. For discussion purposes, let the mobile
node 115 be associated with wireless gateway "WG-1," access point
"AP-2," and network access gateway "NAG-1."
Sometime during the course of normal operations, the mobile node
115 roams out of the service area of WG "WG-1" and into the service
area of another WG, for example, WG-2 (block 524). The AP "AP-2"
can then detect the IP address of the mobile node 115 (block 526).
Since the mobile node 115 already has an IP address that it
maintains for as long as it has a session with the WAWLAN 200, the
mobile node 115 does not need to acquire a new IP address. A
wireless gateway (WG), such as the WG-2, can detect the presence of
the mobile node 115 in the WC and obtain the mobile node's IP
address (block 528). The WG "WG-2" can then inform the mobile
node's anchor NAG of the change in WG (block 530). For example, the
WG "WG-2" can transmit a message to the anchor NAG of the mobile
node 115, NAG-1, to inform the NAG "NAG-1" of the change from WG
"WG-1" to WG "WG-2" (block 530). The NAG "NAG-1" can update its
internal forwarding information to reflect the change from WG
"WG-1" to WG "WG-2."
When a mobile node roams from the service area of a first WG into a
service area of a second WG, the first WG can delete information
that it may have regarding the mobile node. There can be several
ways to detect when to delete the information. A timer can be used
to determine when to delete the information. For example, a timer
can be associated with each mobile node entry in a WG. The timer
can be reset each time that there is an access to the information
about the mobile node. Therefore, if a mobile node's timer is
permitted to expire, then the information for the mobile node has
not been accessed for an extended amount of time and can be
deleted. The value of the timer can be determined through
subscriber authentication process and/or pre-configured operational
parameters on the WG. Alternatively, when the mobile node roams
into the operating area of the second WG and the events described
in the sequence of events 520 have successfully completed, the
second WG can transmit a message to the first WG to inform the
first WG to delete the information that it may have stored
regarding the mobile node.
With reference now to FIG. 5c, there is shown a diagram
illustrating a sequence of events 540 in a transmittal of a packet
from a first mobile node (MN-1) to a second mobile node (MN-2),
according to a preferred embodiment of the present invention. For
discussion purposes, let the first mobile node be associated with
wireless gateway "WG-1," access point "AP-2," and network access
gateway "NAG-1." Furthermore, let the second mobile node be
associated with wireless gateway "WG-2," access point "AP-1," and
network access gateway "NAG-2." In other words, the mobile node 115
powers up and becomes associated as listed above (block 542).
The first mobile node, MN-1, sends a packet to the second mobile
node, MN-2, (block 544) and the packet is transmitted wirelessly to
the AP-2, the AP of the first mobile node. Due to the dual-tier
architecture, the AP "AP-2" sends the packet to the WG "WG-1"
(block 546). For example, the sending of the packet from the AP
"AP-2" to the WG "WG-1" can be accomplished via tunneling. The WG
"WG-1" examines the packet based upon a decoding of the source
address of the packet (the first mobile node, MN-1) forwards the
packet to the anchor NAG of the first mobile node (NAG-1), if the
NAG "NAG-1" is active (on-line) (block 548). The forwarding of the
packet can be accomplished by creating an Ethernet frame and
transmitting the Ethernet frame via the Ethernet switch 285 (FIG.
2c). If the anchor NAG, NAG-1, is inactive (offline), then the
packet can be dropped. If a binding for the source address of the
packet is not found, the packet can also be dropped.
When the packet arrives at the anchor NAG "NAG-1," the packet may
undergo an optional authentication process, performed by the anchor
NAG "NAG-1." The authentication process can involve the forwarding
of the packet to an authentication server that will result in the
first mobile node, MN-1, being securely connected to the
authentication server and the authentication server verifying the
status of the first mobile node, MN-1, and the account status of
the subscriber using the first mobile node, MN-1. Once the first
mobile node, MN-1, and its user have been authenticated, security
features at the anchor NAG "NAG-1," such as a firewall, can be
opened up for the first mobile node, MN-1.
The anchor NAG of the first mobile node, NAG-1, can then send the
packet to the anchor NAG of the second mobile node, NAG-2 (block
550). When the anchor NAG of the second mobile node, NAG-2,
receives the forwarded packet, the anchor NAG "NAG-2," can also
optionally authenticate the packet. The anchor NAG for the second
mobile node, NAG-2, can look in its stored information to determine
a proper forwarding path for the packet to the second mobile unit,
MN-2. Under normal operating conditions, the anchor NAG for the
second mobile unit, NAG-2, already knows with which WC the second
mobile node, MN-2 resides. This is due to when the WG-2 detected
the presence of MN-2. If there is no forwarding path for the second
mobile unit, MN-2, the anchor NAG "NAG-2" can broadcast an address
resolution request through the Ethernet switch 285 to obtain the
address of the WG that is currently serving MN-2. With the
forwarding path, the anchor NAG "NAG-2" can send the packet to the
WG "WG-2" (block 552). The packet can then be send to the AP "AP-1"
(block 554) and subsequently arrives at the second mobile node,
MN-2 (block 556).
With reference now to FIG. 5d, there is shown a diagram
illustrating a sequence of events 560 in a transmittal of a packet
from a first mobile node (MN-1) to a second mobile node (MN-2),
wherein the first mobile node, MN-1, roams into the operating area
of a different WG after it initiates the transmission of the packet
to the second mobile node, MN-2, according to a preferred
embodiment of the present invention. For discussion purposes, let
the first mobile node be associated with wireless gateway "WG-1,"
access point "AP-1," and network access gateway "NAG-1."
Furthermore, let the second mobile node be associated with wireless
gateway "WG-2," access point "AP-1," and network access gateway
"NAG-2." In other words, the mobile node 115 powers up and becomes
associated as listed above (block 562).
The first mobile node, MN-1, sends a packet to the second mobile
node, MN-2, (block 564) and while the packet is transmitted
wirelessly to the AP "AP-1," the first mobile node, MN-1, roams
into a service area of the WG "WG-2" (block 566). As the first
mobile node, MN-1, roams into the service area of the WG "WG-2,"
the packet (and any subsequent packets) can still be transmitted as
long as a binding for the first mobile node, MN-1, is not removed
at the WG "WG-1." As a result of the roaming, the first mobile
node, MN-1, becomes associated with WG "WG-2," access point "AP-2,"
and network access gateway "NAG-1." Refer to the discussion of the
sequence of events 520 shown in FIG. 5b for a detailed discussion
of the sequence of events involved in roaming.
The AP "AP-2," the newly associated AP for the first mobile node,
MN-1, receives a packet from the first mobile node, MN-1, (block
568) and sends the packet to WG "WG-2" (bock 570). The WG "WG-2"
examines the source address of the packet based upon a decoding of
the source address of the packet, forwards the packet to the anchor
NAG of MN-1 "NAG-1" (block 572). The packet can be forwarded by
creating an Ethernet frame and transmitting the Ethernet frame via
the Ethernet switch 285. If the anchor NAG "NAG-1," is offline, the
packet can be dropped. Furthermore, if a binding for the source
address of the packet is not found, the packet can be dropped.
When the packet arrives at the anchor NAG "NAG-1," the packet may
undergo an optional authentication process, performed by the anchor
NAG "NAG-1." The authentication process can involve the forwarding
of the packet to an authentication server that will result in the
first mobile node, MN-1, being securely connected to the
authentication server and the authentication server verifying the
status of the first mobile node, MN-1, and the account status of
the subscriber using the first mobile node, MN-1. Once the first
mobile node, MN-1, and its user have been authenticated, security
features at the anchor NAG "NAG-1," such as a firewall, can be
opened up for the first mobile node, MN-1. The anchor NAG "NAG-1,"
can then pass the packet to the anchor NAG of the second mobile
node, NAG-2 (block 574).
When the anchor NAG of the second mobile node, NAG-2, receives the
forwarded packet, the anchor NAG "NAG-2," can also optionally
authenticate the packet. The anchor NAG for the second mobile node,
NAG-2, can look in its stored information to determine a proper
forwarding path for the packet to the second mobile unit, MN-2.
Under normal operating conditions, the anchor NAG for the second
mobile unit, NAG-2, already knows with which WC the second mobile
node, MN-2 is associated. This is due to when the WG-2 detected the
presence of MN-2. If there is no forwarding path for the second
mobile unit, MN-2, the anchor NAG "NAG-2" can broadcast an address
resolution request through the Ethernet switch 285 to obtain the
address of the WG that is currently serving MN-2. With the
forwarding path, the anchor NAG "NAG-2" can send the packet to the
WG "WG-2" (block 576). The packet can then be send to the AP "AP-1"
(block 578) and subsequently arrives at the second mobile node,
MN-2 (block 580).
Although the present invention and its advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations can be made herein without departing
from the spirit and scope of the invention as defined by the
appended claims.
Moreover, the scope of the present application is not intended to
be limited to the particular embodiments of the process, machine,
manufacture, composition of matter, means, methods and steps
described in the specification. As one of ordinary skill in the art
will readily appreciate from the disclosure of the present
invention, processes, machines, manufacture, compositions of
matter, means, methods, or steps, presently existing or later to be
developed, that perform substantially the same function or achieve
substantially the same result as the corresponding embodiments
described herein may be utilized according to the present
invention. Accordingly, the appended claims are intended to include
within their scope such processes, machines, manufacture,
compositions of matter, means, methods, or steps.
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